/*
 * Copyright 2017 Baidu, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package com.engine.modules.ytht.util;

import java.util.Base64;

public class SuperBase64Util {
	private static final char[] ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
			.toCharArray();

	private static final char LAST2BYTE = (char) Integer.parseInt("00000011", 2);
	private static final char LAST4BYTE = (char) Integer.parseInt("00001111", 2);
	private static final char LAST6BYTE = (char) Integer.parseInt("00111111", 2);
	private static final char LEAD6BYTE = (char) Integer.parseInt("11111100", 2);
	private static final char LEAD4BYTE = (char) Integer.parseInt("11110000", 2);
	private static final char LEAD2BYTE = (char) Integer.parseInt("11000000", 2);
	private static final char[] ENCODE_TABLE = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
			'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
			'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1',
			'2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };

	private static int[] toInt = new int[128];

	static {
		for (int i = 0; i < ALPHABET.length; i++) {
			toInt[ALPHABET[i]] = i;
		}
	}

	private SuperBase64Util() {
		throw new IllegalStateException(this.getClass().getName());
	}

	/**
	 * Base64 encoding.
	 *
	 * @param from The src data.
	 * @return cryto_str
	 */
	public static String encode(byte[] from) {
		StringBuilder to = new StringBuilder((int) (from.length * 1.34) + 3);
		int num = 0;
		char currentByte = 0;
		for (int i = 0; i < from.length; i++) {
			num = num % 8;
			while (num < 8) {
				switch (num) {
				case 0:
					currentByte = (char) (from[i] & LEAD6BYTE);
					currentByte = (char) (currentByte >>> 2);
					break;
				case 2:
					currentByte = (char) (from[i] & LAST6BYTE);
					break;
				case 4:
					currentByte = (char) (from[i] & LAST4BYTE);
					currentByte = (char) (currentByte << 2);
					if ((i + 1) < from.length) {
						currentByte |= (from[i + 1] & LEAD2BYTE) >>> 6;
					}
					break;
				case 6:
					currentByte = (char) (from[i] & LAST2BYTE);
					currentByte = (char) (currentByte << 4);
					if ((i + 1) < from.length) {
						currentByte |= (from[i + 1] & LEAD4BYTE) >>> 4;
					}
					break;
				default:
					break;
				}
				to.append(ENCODE_TABLE[currentByte]);
				num += 6;
			}
		}
		if (to.length() % 4 != 0) {
			for (int i = 4 - to.length() % 4; i > 0; i--) {
				to.append("=");
			}
		}
		return to.toString();
	}

	/**
	 * Translates the specified Base64 string into a byte array.
	 *
	 * @param s the Base64 string (not null)
	 * @return the byte array (not null)
	 */
	public static byte[] decode(String s) {
		int delta = 0;
		if (s.endsWith("==")) {
			delta = 2;
		} else if (s.endsWith("=")) {
			delta = 1;
		}
		byte[] buffer = new byte[s.length() * 3 / 4 - delta];
		int mask = 0xFF;
		int index = 0;
		for (int i = 0; i < s.length(); i += 4) {
			int c0 = toInt[s.charAt(i)];
			int c1 = toInt[s.charAt(i + 1)];
			buffer[index++] = (byte) (((c0 << 2) | (c1 >> 4)) & mask);
			if (index >= buffer.length) {
				return buffer;
			}
			int c2 = toInt[s.charAt(i + 2)];
			buffer[index++] = (byte) (((c1 << 4) | (c2 >> 2)) & mask);
			if (index >= buffer.length) {
				return buffer;
			}
			int c3 = toInt[s.charAt(i + 3)];
			buffer[index++] = (byte) (((c2 << 6) | c3) & mask);
		}
		return buffer;
	}

	public static String encodeToString(byte[] from) {
		// 对字节数组Base64编码
		Base64.Encoder encoder = Base64.getEncoder();
		// 返回Base64编码过的字节数组字符串
		return encoder.encodeToString(from);
	}
	
	
}
